The purpose of the proposed research is to determine the prevalence of chlamydia and gonorrhea infection among young patients (age 13-30), attending an urban primary care health clinic in Hartford, Connecticut. By testing a broad sample of patients, including those with and without symptoms of sexually transmitted diseases (STDs), we will be able to estimate the prevalence of chlamydia and gonorrhea among patients in this age group attending the Burgdorf Clinics, and to determine the cost-effectiveness of screening for STDs in this setting. The results of this study may enable us to develop a clinical prediction model to help target STD screening efforts to those at high risk.